Device for exchanging a polishing disc

ABSTRACT

A device for exchanging a polishing disc that coated with a polishing agent during operation includes the polishing disc being made from a foam material, foam rubber, felt or lambskin and fastened to a support plate of a polishing tool held on a robot. The device includes an exchanging device having at least one dispenser in which a stack of polishing discs is arranged. The dispenser has a discharge opening, the clear width of which is smaller than the assigned dimension of the polishing disc and larger than the assigned dimension of the support plate. An axially movable sliding device on which the stack rests is provided on the side facing away from the discharge opening.

BACKGROUND AND SUMMARY OF THE INVENTION

Exemplary embodiments of the invention relate to a device for exchanging a polishing disc.

Polishing discs are used to finish the surfaces of workpieces. The polishing discs are made of a very soft material, for example foam, foam rubber, felt or lambskin. They are fastened to the support plate of the polishing tool by means of connecting elements, in particular a Velcro fastener.

The opposite working side of the polishing disc is usually provided with a highly viscous polishing paste, wherein it must be ensured that when the polishing disc is attached to the support plate, the polishing disc is attached to the support plate with the correct side.

For easier handling when replacing the polishing disc, i.e., to make it easier to remove, the polishing disc protrudes beyond the support plate at the edge.

For an optimum polishing result, the amount of polishing agent applied to the working side of the polishing disc is decisive. For a new polishing disc, a larger amount of polishing agent is first applied and worked into the polishing disc. In subsequent polishing operations, only a small amount of polishing agent is then applied for the respective polishing process, wherein preferably flat workpieces are polished by orbital, rotational and vibrating movements of the polishing tool.

In order to avoid polish splashes, it is important to position the polishing disc or polishing paste exactly, as well as its pattern on the polishing disc. Furthermore, the contact pressure and polishing time are decisive for the polishing result.

It is necessary to change the polishing disc if, for example, the polishing disc is clogged with clear lacquer or base lacquer with which the workpiece is coated, or if the polishing disc's service life has expired or the polishing agent has dried up due to longer breaks.

Replacing the polishing disc has so far been very time-consuming and requires extremely careful work due to the operational contamination. This means that the replacement of the polishing disc, which has been carried out up to now, is a clear obstacle to the cost optimization of the entire polishing process that is always required.

Exemplary embodiments of the invention are directed to a device that allows the replacement of a polishing disc in a shorter time and automatically.

By means of this device, the polishing disc, which practically is worn and held on the support plate of the grinding tool, is automatically replaced, i.e., exchanged for a new polishing disc.

For this purpose, only the polishing tool, usually the arm of the the robot, is to be moved with the connected support plate into the area of a removal opening of a dispenser until contact is made with the polishing disc lying at the top, wherein the positive connection is produced by the corresponding Velcro layers of the support plate on the one hand and the polishing disc on the other hand by means of appropriate pressure.

A sliding device arranged according to the invention on the side of the exchanging device opposite the removal opening, on which the stack of polishing discs rests, serves as an abutment in this case.

After a removal of the corresponding polishing disc, the remaining stack is shifted by the sliding device in such a way that the uppermost polishing disc reaches a removal position.

According to a first embodiment variant, the clear dimension of the removal opening is smaller than the associated outer dimension of the polishing discs, so that a stop is formed that limits the displacement path of the stack by means of the sliding device. In an embodiment variant, the formation of such a stop is not necessary, since the sliding device itself is set up in such a way that it does not push the stack of polishing discs too far forward.

The outer dimension of the support plate, on the other hand, is smaller than the clear dimension of the removal opening, so that the support plate can enter the dispenser unhindered for connection with the polishing disc. The capacity of the dispenser is such that a sufficient number of polishing discs is stored for one working shift. The sliding device can be driven pneumatically, hydraulically or electromechanically.

An extractor device is connected upstream of the exchanging device, by means of which the worn polishing disc is removed from the support plate. This extractor device is equipped with a clamping device, which can consist of gripping pliers, finger pliers or parallel grippers, and by means of which the polishing disc projecting over the edge of the support plate is removed from the support plate.

In this process, the clamping device is brought into a clamping position by a mechanical contact or a light barrier after a movement of the polishing tool into the effective range of the extractor device, preferably by laser detection. The polishing tool is then preferably moved vertically into the area of the exchanging device, wherein the Velcro connection between the polishing disc and the support plate is released.

Furthermore, a collecting container can be provided to hold the polishing disc detached from the support plate. The collecting container, which may be lined with a waste bag, is designed in such a way that it can be moved from the working area of the polishing tool to the area of the exchanging device.

According to a further idea of the invention, the exchanging device has several dispensers arranged on a table at equal distances from each other, wherein the table, which is designed as a round or linear table, is movable in cycles and the respective dispenser can be brought into correspondence with the sliding device. Below the table, a space can be provided for storing dispensers which are supplied ready-made and equipped with polishing discs.

Especially polishing tools that perform orbital and/or eccentric movements can remain in one position indefinitely if the drive power is interrupted. They must therefore be aligned with the polishing disc to be picked up, for which purpose an alignment station for the support plate is located above the exchanging device.

This alignment station has a prism-shaped receptacle that is moved in a horizontal movement towards the support plate and positions it in the center position, exactly to the axis of the exchanging device, by means of an orbital or eccentric movement. Afterwards the prism-shaped holder moves back into a parking position.

The movement sequences of the polishing tool, i.e., the robot, are computer-controlled, wherein the necessity of changing the polishing disc is also detected by a corresponding sensor system.

The automatic work sequence also includes the application of a polishing agent, especially a polishing paste, to the polishing disc. For this purpose, a dosing device is arranged downstream of the exchanging device, which is equipped with a nozzle tip that allows an exact application to the working side of the polishing disc and closes it without dripping.

Alternatively, the polishing agent can be dosed through a polishing agent nozzle from the rear side into the polishing disc, which is preferably designed as a polishing sponge, or through the polishing disc.

This dosing device is equipped with a storage container connected to the nozzle tip via a supply line.

The nozzle tip can be arranged on the robot arm, in the area of the support plate, wherein the polishing disc is provided with the polishing agent after a rotational movement in a time- and path-optimized manner.

Alternatively, the nozzle tip can be placed above the exchanging device, in which case the polishing tool moves towards the nozzle tip.

The output quantity on the polishing disc is also computer-controlled.

A necessary filling of the dispenser with polishing discs can be carried out by an operator, wherein a visual, acoustic or electrical signal gives a corresponding indication to the person. An electronic message can also be sent from the system control, i.e., the computer. In addition, the operator can supply several devices accordingly.

The computer can be used to solve logistical tasks or initiate orders, wherein the consumption of polishing discs and polishing agents per processed workpiece, shift or time period is determined and reported, which ultimately contributes to a continuous improvement of the work process.

This applies equally to the detection of the consumption of polishing discs and polishing agents, which can be used to detect maintenance measures, such as changing the support plate due to wear.

According to another aspect, the working area of the polishing tool is separated from the set-up area, i.e., the area where the exchanging device is loaded. Here the working area is secured by a safety fence, light barriers, light curtains, grids and/or doors, wherein when the doors are opened, the polishing tool is stopped in its movement or moved to a basic position and switched off.

According to an alternative embodiment variant, the clamping device is designed as a jaw tool with at least one displaceable piston with a piston tip that can be pressed laterally into the polishing disc.

According to a further alternative embodiment variant, the clamping device has a main body with a circular opening serving as a toothed pulley holder, the main body having an inlet opening widening away from the toothed pulley, into which the support plate of a polishing tool with a polishing disc adhering thereto can be inserted, and an outlet opening widening away from the toothed pulley, through which a polishing disc released from the support plate can be removed from the clamping device.

According to another idea, the dispenser has limiting rods fixed to a floor and an intermediate floor penetrated by the limiting rods, on which the polishing discs can be stacked, wherein the length of the limiting rods forming a receiving cage for the polishing discs is designed to be adaptable to the stacking height of the polishing discs.

The floor is preferably firmly connected to a positioning rod which, when the polishing tool is lowered, can be moved relative to the stacked polishing discs with the support plate arranged on it until the support plate comes into contact with the uppermost of the polishing discs and can be locked in this position.

According to a further alternative embodiment variant of the invention, the device has an exchanging device with at least one dispenser, wherein the dispenser has a magazine shaft positioned at an incline, with an upper filling region for supporting at least one polishing disc, which can be brought along the magazine shaft into a removal station at a lower end of the magazine shaft, to which the support plate can be moved for attaching the polishing disc to the support plate.

The removal station has position pins for the exact positioning of the polishing disc in a preferred further development.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiment examples of the invention are described below using the attached drawings, wherein:

FIGS. 1 and 2 show the use of a device according to the invention in different schematic views;

FIG. 3 shows a detail of the device in a perspective side view;

FIG. 4 shows an enlarged section of the part according to FIG. 3;

FIG. 5 shows another detail of the device in a perspective view;

FIG. 6 shows another detail of the device in a perspective view;

FIG. 7 shows an enlarged section of the detail according to FIG. 6;

FIG. 8 shows a sectional view through an embodiment variant of a clamping device designed as a jaw tool;

FIG. 9 shows a partially sectional side view through another embodiment variant of a clamping device;

FIG. 10 shows a side view of an embodiment variant of a dispenser;

FIG. 11 shows a sectional view through the dispenser shown in FIG. 10;

FIG. 12 shows a perspective view of another embodiment variant of a dispenser, and

FIG. 13 shows a perspective detail view of the section designated XIII in FIG. 12.

DETAILED DESCRIPTION

In FIGS. 1 and 2 there is a device for exchanging a sheet-shaped polishing disc 8, usually 10-20 mm thick, coated with a polishing agent when in operation, which is attached to a support plate 4 of a polishing tool held on a robot 1 by means of connecting means.

According to the invention, the device has an exchanging device 2 positioned on a worktable 6, which in the example has several dispensers 3 held on a rotary table, which can be brought at equal distances to each other in cycles into the transfer area with the support plate 4.

A partition wall 5 separates a set-up area 15 from a working area 16, wherein in working area 16 the robot 1 is arranged with a part of the exchanging device 2, while set-up area 15 is intended to equip exchanging device 2 with dispensers 3 by means of an operator 7.

A dispenser 3 is shown as a detail in FIG. 3. In the example, dispenser 3 has several, specifically four, limiting rods 11, which form a lateral fixation for polishing discs 8 stacked in the formed interior space.

These polishing discs 8 have, in a manner known per se, a connecting surface and opposite them a working surface, wherein the connecting surface is provided in particular with a Velcro layer which can be brought into contact with a Velcro layer of the support plate 4.

The polishing discs 8 are accommodated in the dispenser 3 in such a way that the connecting surface of the uppermost polishing disc 8 is exposed, while the lowermost polishing disc 8 is supported with its working surface on a sliding device 9, which is axially displaceable and in so doing moves the stack so far that after removal of the uppermost polishing disc 8 the following polishing disc 8 is brought into a removal position.

Especially in FIG. 4 it can be clearly seen that in the area of the removal, i.e., in the area of the upper polishing disc 8, stops 10 are attached to the projecting ends of the rods 11, which are arranged opposite each other at a clear distance which is smaller than the assigned outer dimension of the polishing disc 8, which is designed to be flexible, i.e., bendable.

To connect the polishing disc 8 with the facing side of the support plate 4, the support plate 4 is brought under pressure against the connecting surface of the polishing disc 8, wherein the outer dimension of the support plate 4 is smaller than the clear distance between the opposing stops 10. This results in an edge projection of the polishing disc 8 relative to the support plate 4.

In order to apply the pasty polishing agent to the working surface of the polishing disc 8, a dosing device 12 is arranged downstream of the exchanging device 2, which is shown as a detail in FIG. 5.

This dosing device 12 has a cartridge 13 filled with the polishing agent and a nozzle 14 with which the polishing agent can be applied to the working surface of the polishing disc 8 in a defined quantity and in a defined application pattern.

The dosing device 12 can be positioned stationary, in the area of the exchanging device 2 or on the robot arm of the robot 1, wherein the support plate 4 is brought into the application area of the nozzle 14 by a corresponding movement.

FIG. 6 shows an alignment station 17 having a prism-shaped receptacle 18 that can be moved horizontally in the direction of the dispenser 3, by means of which the support plate can be brought into a position with the same axis as the dispenser 3 or the polishing discs 8.

FIG. 7 shows an enlarged view of the upper area of the alignment station 17 having the prism-shaped receptacle 18.

It can be seen that the receptacle 18 can be moved with the help of a slide, wherein the movement can be carried out by a pneumatic, hydraulic or electromechanical drive.

In operation, the support plate, whose base is circular, lies with its edge against the prism formed, which thus forms a centering for the support plate.

According to a further embodiment variant, in which the polishing tool on the robot arm of robot 1 can be controlled electronically on the basis of an absolute value encoder, the use of such an alignment station 17 can be dispensed with, since the angle measurement allows robot arm of robot 1 to be positioned exactly centrally above the exchanging station.

According to a further embodiment variant, in which the polishing tool on the robot arm of robot 1 can be controlled electronically incrementally, the use of the alignment station 17 is only necessary if the power supply to the robot arm of robot 1 has been interrupted.

It is preferable to have an extractor device upstream of the exchanging device 2, with which a polishing disc 8 can be removed from the support plate 4.

For this purpose, the extractor device is equipped with a clamping device with which, according to one embodiment variant, a marginal area of the polishing disc 8 projecting from the support plate 4 can be clamped.

The clamping device can be actuated for closing by laser detection, a mechanical contact or a light barrier, depending on the position of the support plate 4.

Below the clamping device, a collecting container can be arranged to accommodate the polishing disc 8 which is released from the support plate 4.

According to a preferred embodiment variant, as shown in FIG. 8, the clamping device of the extractor device is designed as jaw tool 19.

As shown in FIG. 8, the jaw tool 19 has a main body 20 with a preferably circularly shaped receiving opening for receiving the polishing disc 8.

To remove the polishing disc 8 from the support plate 4, the polishing disc 8 attached to the support plate 4 is pressed into the opening of the jaw tool 19.

Subsequently, a piston tip 22 of at least one preferably pneumatically displaceable piston is pressed laterally into the polishing disc 8 and thus holds the polishing disc 8 firmly in engagement in the jaw tool 19.

It is also conceivable to arrange several such pistons 21 with piston tips 22 for fixing the polishing disc 8.

After the piston tip 22 or the piston tips 22 have been pressed laterally into the polishing disc 8, the support plate 4 is moved away from the polishing disc 8 perpendicularly to the fixing surface of the support plate 4, thus releasing the polishing disc 8 from the support plate 4.

Then the pistons 21 are returned to their initial position. During this process, the piston tip 22 or the piston tips 22 move back out of engagement with the polishing disc 8.

The polishing disc 8 can then preferably be disposed of downwards into a collecting container positioned below the jaw tool 19.

According to another embodiment variant, as shown in FIG. 9, the clamping device is provided with a toothed pulley 25.

As shown in FIG. 9, the clamping device shown here has a main body 26 with a circular opening serving as a toothed pulley holder, wherein above the toothed pulley 25 an inlet opening 27 widening towards a polishing tool 24 and an outlet opening 28 widening downwards, i.e., away from the toothed pulley 25, is formed.

To remove the polishing disc 8, the polishing disc 8 is also moved by moving the polishing tool 24 in the direction of the toothed pulley 25 until the polishing disc 8 is pressed through the inlet opening 27 into the toothed pulley 25.

The diameter of the toothed pulley 25 is slightly smaller than the diameter of the polishing disc 8.

The polishing tool 24 is then moved out of the inlet opening 27 back to its initial position, in FIG. 9 upwards. During this process, the polishing disc 8 gets caught in the teeth of the toothed pulley 25, so that when the support plate 4 is moved further upwards together with the polishing tool 24, the polishing disc 8 is released from the support plate 4.

The polishing disc 8 remains stuck in the teeth of the toothed pulley 25 until the next polishing disc 8 is pressed through the inlet opening 27 and the toothed pulley 25 and the previously stuck polishing disc 8 is released from the engagement with the toothed pulley 25.

In this embodiment example, a collecting container can also be positioned below the clamping device to collect the used or worn polishing disc 8.

As shown in FIGS. 8 and 9 below, polishing disc 8 has a channel 23 which preferably extends centrally and perpendicularly to the polishing surface of polishing disc 8.

This channel 23 is used to accommodate an application nozzle 29, which is located centrally in the support plate 4 and which is connected to a polishing agent reservoir. Through this polishing agent nozzle 29 the polishing agent can be dosed into the polishing disc 8.

Further special embodiment variants of a dispenser 31, 42 are shown in FIGS. 10 to 13.

In the embodiment variant shown in FIGS. 10 and 11, the dispenser 31 has several limiting rods 11, similar to the embodiment variant in FIG. 3, which form a lateral fixing for polishing discs 8 stacked in the formed interior space.

The limiting rods 11 of the dispenser 31 are fixed on a floor 32 and pass through an intermediate floor 33 on which the polishing discs 8 can be stacked. The length of the part of the limiting rods 11 projecting upwards from the intermediate floor 33 is designed to be adaptable to the stacking height of the polishing discs 8.

For this purpose the floor 32 is firmly connected to a positioning rod 34 as can be seen clearly in FIG. 11.

This positioning rod 34 has a pressure surface 35 at its upper end close to the polishing machine 24, which, when the polishing tool 24 is lowered with the support plate 4 arranged on it, is pressed downwards relative to the stacked polishing discs 8, in FIG. 11, until the support plate 4 comes to rest against the uppermost of the polishing discs 8, thus connecting the uppermost polishing disc 8 to the support plate 4 in an adhesive manner, preferably by means of a Velcro connection.

The vertical displacement of the positioning rod 34 is accompanied by a lowering of the limiting rods 11.

The polishing discs 8 are not stacked on the floor 32, to which the limiting rods 11 are attached, but on an intermediate floor 33 located above the floor 32, through which the limiting rods 11 pass.

In contrast to floor 32, to which the limiting rods 11 are attached, this intermediate floor 33 always remains at the same height relative to the starting position of the support plate 4.

The positioning rod 34 is designed as a locking shaft at least in the lower area below the base 32, with ratchet teeth 36.

These ratchet teeth 36 are engaged by a locking pawl 37 fixed to a lower base 38, which is connected to the base 32 by connecting rods 39, with which the positioning rod 34 is locked in the respective position in which the polishing disc 8, which was previously received by the support plate 4, was accommodated.

This allows the distance between the pressure surface 35 of the positioning rod 34 and the upper edge of the respective uppermost polishing disc 8 to remain constant until all polishing discs 8 have been removed from the dispenser 3.

In order to refill the dispenser 31 with polishing discs 8, the locking pawl 37 can be released by turning the positioning rod 34, for example by means of an operating lever 41 attached to it perpendicular to its longitudinal extension, and moved back to its initial position by the force of springs 40 attached to the connecting rods 39 of the floor 32 with the lower base 38.

In doing so, the limiting rods 11 are moved upwards relative to the intermediate floor, thus forming a cage which can be filled with new polishing discs 8 until the stack of polishing discs 8 reaches the upper edge of the limiting rods 11 again.

In the alternative embodiment variant, as shown in FIGS. 12 and 13, the dispenser 42 has an inclined magazine shaft 43 into which polishing discs 8 can be inserted in an upper filling area 44.

The polishing discs 8 then slide along the magazine shaft 43 to a removal station 47.

At this removal station 47, shown in detail in FIG. 13, positioning pins 48 are provided for the exact positioning of the polishing discs 8. The polishing tool 24 with the support plate 4 arranged on it can be moved up to this removal station 47 and thus accommodate a respective polishing disc 8.

As further shown in FIG. 12, the magazine shaft 43 extends through a protective wall 45 with an opening 46, with a set-up area 44 of the magazine 42 being positioned on the side opposite the protective wall 45 as the removal station 47.

In order to prevent more than one polishing disc 8 being present on top of each other at the removal station 47, a monitoring element, for example in the form of a light barrier, is preferably provided in the area of removal station 47.

Although the invention has been illustrated and described in detail by way of preferred embodiments, the invention is not limited by the examples disclosed, and other variations can be derived from these by the person skilled in the art without leaving the scope of the invention. It is therefore clear that there is a plurality of possible variations. It is also clear that embodiments stated by way of example are only really examples that are not to be seen as limiting the scope, application possibilities or configuration of the invention in any way. In fact, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete manner, wherein, with the knowledge of the disclosed inventive concept, the person skilled in the art is able to undertake various changes, for example, with regard to the functioning or arrangement of individual elements stated in an exemplary embodiment without leaving the scope of the invention, which is defined by the claims and their legal equivalents, such as further explanations in the description.

LIST OF REFERENCE NUMERALS

-   -   1 Robot     -   2 Exchanging device     -   3 Dispenser     -   4 Support plate     -   5 Partition wall     -   6 Worktable     -   7 Operator     -   8 Polishing disc     -   9 Sliding device     -   10 Stop     -   11 Limiting rod     -   12 Dosing device     -   13 Cartridge     -   14 Application nozzle     -   15 Set-up area     -   16 Working area     -   17 Alignment station     -   18 Receptacle     -   19 Jaw tool     -   20 Main body     -   21 Piston     -   22 Piston tip     -   23 Channel     -   24 Polishing tool     -   25 Toothed pulley     -   26 Main body     -   27 Inlet opening     -   28 Outlet opening     -   29 Polishing agent nozzle     -   30 Velcro coating     -   31 Dispenser     -   32 Floor     -   33 Intermediate floor     -   34 Positioning rod     -   35 Pressure surface     -   36 Ratchet teeth     -   37 Locking pawl     -   38 Floor     -   39 Connecting rod     -   40 Spring     -   42 Operating lever     -   42 Dispenser     -   43 Magazine shaft     -   44 Set-up area     -   45 Protective wall     -   46 Opening     -   47 Removal station     -   48 Positioning pin 

1-22. (canceled)
 23. A device for exchanging a polishing disc that includes a foam material, foam rubber, felt, or lambskin, is coated with a polishing agent during operation, and is attached to a support plate of a polishing tool held on a robot, the device comprising: an exchanging device having at least one dispenser, in which a stack of polishing discs is arranged, wherein the at least one dispenser has a removal opening, a clear width of the removal opening is larger than an associated dimension of the support plate; and an axially movable sliding device, on which the stack of polishing discs rests, is arranged on a side of the exchanging device that faces away from the removal opening of the at least one dispenser.
 24. The device of claim 23, wherein the clear width of the removal opening of the at least one dispenser is smaller than an associated dimension of the polishing disc.
 25. The device of claim 23, further comprising: an extractor connected upstream of the exchanging device, wherein the extractor is configured to remove the polishing disc from the support plate.
 26. The device of claim 25, wherein the extractor includes a clamping device configured to clamp an edge region of the polishing disc projecting beyond the support plate.
 27. The device of claim 26, wherein the clamping device is actuatable for closing in a coordinate-dependent manner by laser detection, a mechanical contact or a light barrier, depending on a position of the support plate.
 28. The device of claim 25, wherein the extractor includes a clamping device configured to laterally clamp the polishing disc.
 29. The device of claim 28, wherein the clamping device is a jaw tool having at least one displaceable piston with a piston tip configured to be pressed laterally into the polishing disc.
 30. The device of claim 28, wherein the clamping device comprises: a main body with a circular opening serving as a toothed pulley holder, wherein the main body has an inlet opening widening away from a toothed pulley, into which the support plate of the polishing tool with the polishing disc adhering thereto is insertable; and an outlet opening widening away from the toothed pulley, through which a polishing disc released from the support plate is removable from the clamping device.
 31. The device of claim 23, further comprising: a collecting container arranged below the clamping device, wherein the collecting container is configured to receive a polishing disc released from the support plate.
 32. The device of claim 23, further comprising: an alignment station configured for positionally accurate positioning of the support plate, wherein the alignment station is arranged upstream of the exchanging device, and wherein the alignment station has a prism-shaped receptacle.
 33. The device of claim 23, further comprising: a dosing device arranged downstream of the exchanging device, wherein the dosing device includes a reservoir of polishing agent and an application nozzle connected to the reservoir.
 34. The device of claim 23, wherein the at least one dispenser includes several dispensers that are positioned on a table and are movable in cycles.
 35. The device of claim 34, wherein the table is a rotary table or linear table.
 36. The device of claim 34, wherein the several dispensers are arranged at equal distances from each other.
 37. The device of claim 23, wherein the exchanging device is enclosed.
 38. The device of claim 37, wherein the enclosed exchanging device has a removal opening for changing the at least one dispenser.
 39. The device of claim 23, wherein the exchanging device or the robot is connected to a computer.
 40. The device of claim 23, further comprising: sensors configured to control the robot and the exchanging device.
 41. The device of claim 23, wherein the at least one dispenser comprises: a floor; an intermediate floor; and limiting rods fixed to the floor and the intermediate floor, wherein the limiting rods pass through the intermediate floor, the limiting rods form a receiving cage for the stack of polishing discs, which are stacked on the intermediate floor, and wherein a length of the limiting rods are adaptable to a stacking height of the stack of polishing discs.
 42. The device of claim 41, wherein the floor is fixedly connected to a positioning rod, wherein when the polishing tool with the support plate is lowered the positioning rod is moveable relative to the stack of polishing discs until the support plate rests against an uppermost one of the stack of polishing discs and the support plate is locked in this position.
 43. A device for exchanging a polishing disc that includes a foam material, foam rubber, felt, or lambskin, is coated with a polishing agent during operation, and is attached to a support plate of a polishing tool held on a robot, the device comprising: an exchanging device having at least one dispenser, wherein the at least one dispenser has a magazine shaft positioned at an incline, wherein an upper filling region of the at least one dispenser supports at least one polishing disc; and a removal station, wherein the at least one polishing disc can be moved along the magazine shaft into the removal station at a lower end of the magazine shaft, wherein the support plate is moved to the removal station to attach attaching a new polishing disc to the support plate.
 44. The device of claim 43, wherein the removal station has positioning pins configured for exact positioning of the polishing disc. 